Recent electronic gadgets including cell phones, lap-top personal computers and so on, have, as is well known, protective means for secondary batteries. The protective means are commonly made of an electric resistor element having a positive temperature coefficient (PTC) of resistance. It is desirable that advanced electronic gadgets of the class described earlier perform better in operation, last longer in service life, and exhibit further efficient performance. To cope with the functional demands as stated above, it is desirable that the secondary batteries have higher capacity as well as electric intensity. Correspondingly, it is desirable that the PTC element be able to withstand high electric potential. The current working PTC elements are expected to withstand about 8 volts. To deal with batteries able to withstand much higher electric potential, nonetheless, the PTC element has to have an improved insulation strength, or withstand voltage, especially in the “off” state where the current is limited extremely less. With leading conventional PTC elements, moreover, their matrices are mainly made of solid material including ceramics, polymers, and so on. Most existing PTC elements use either polyethylene composed of polyethylene and carbon black or barium titanate.
Meanwhile, there have been known dielectrophoretic filtering means and methods of dielectrophoretic removal of fine particles from suspension systems. These prior techniques are of practical use to remove effectively as well as selectively fine particles from the suspensions with causing no clogging to recover them with ease. One of the prior dielectrophoretic filtering means is disclosed in, for example patent document 1 enumerated later, in which many dielectric particles are filled between opposing electrodes to cause either local concentration or local reduction in an electric field created across the electrodes, and further there is provided an electric power source to apply across the electrodes an alternating voltage whose frequency is enough to induce dielectrophoretic migration on the dispersed fine particles. Any dielectric particles come into contact or closer encounter with other dielectric particles at sideward locations where the electric field gets the most or the least around the dielectric particles, and then the fine particles in suspensions are collected and captured under dielectrophoretic force into specific sections distinctive in electric field generated near the sideward locations.
Moreover, the patent document 2 listed later discloses an electrode chip available for a microbiological analyzer that makes easily and rapidly a high-sensitive quantitative separation of any specific microorganism in a mixture suspension without drawing upon to the experts. There is provided a reservoir storing antibody fluids therein to feed the antibody fluids into an analyzer chamber where the antibody fluids encounter microorganisms concentrated between the electrodes, making antigen-and-antibody reaction. A processor controller actuates an electric power source to apply an electric potential across the electrodes to concentrate many groups of microorganisms. Of the groups of concentrated microorganisms, just specific group of microorganisms selectively or distinctively reacts with the antibody fluids delivered from the antibody fluids reservoir, thereby getting condensates to be separated from other groups of microorganisms. Analytic means identifies a number of the specific microorganisms, depending on measured variations in conductance between the electrodes.
A current-limiter having a PTC element is conventionally known in which the PTC element is made to get rising in temperature simultaneously through the entire PTC element. Disclosed in, for example the patent document 3 listed later is the PTC current-limiter in which the PTC element is flanked by electrodes that are secured to the opposite sides of the PTC element, one to each side. The PTC element has a raised middle portion and a peripheral portion less in thickness around the raised middle portion. Correspondingly, one of the electrodes is made recessed at a central area with leaving a circular periphery to fit over the raised middle portion of the PTC element. With the construction stated earlier, the PTC element gets large in resistivity at the raised middle portion than at the peripheral portion, so that the temperature rise can be kept uniform through the overall PTC element despite of large radiation rate at the peripheral potion.
The current limiting fuse is conventionally provided by a production process as disclosed in, for example the patent document 4 listed later. Electrodes are secured to forward and aft ends of an insulating tube in a coaxial relation with one another and thereafter an insulating core wound with a fusing element is introduced in the insulating tube through an opening made in an outward end surface of any one of the forward and aft electrodes. After fastening one end of the insulating core wound with a fusing element to any one of the electrodes, the insulating tube is packed with an arc-extinguishing medium. Then, the insulating core is secured at another end thereof to an electrode covering, which is connected to the other electrode. Thus, the insulating core becomes ready for fastening when the electrodes have been once fastened to the insulating tube.
The patent documents 1 to 4 stated earlier refer to the following material information.
Patent document 1: Japanese Patent Laid-Open No. 2003-200081
Patent document 2: Japanese Patent Laid-Open No. 2003-223
Patent document 3: Japanese Patent Laid-Open No. H10-326554
Patent document 4: Japanese Patent Laid-Open No. 2002-270078